Princeton University Departments of Physics and Astrophysics Special Lectures in Cosmology

There are many puzzles confronting present-day observational cosmology, such as the nature of dark matter, the reason for a small cosmological constant (or some other form of "dark energy"), and the origin and initial nature of the irregularities and correlations in the cosmic microwave background. Dwarfing all these (in my opinion) is the very odd nature of the extreme specialness of the Big Bang, in which gravitation is singled out as the one feature of the early universe which accounts for the exraordinary specialness that is an essential feature of the second law of thermodynamics. This talk describes the recent idea of conformal cyclic cosmology (CCC) which takes the conformal (i.e. null-cone) structure of space-time to be primary, being respected by all massless fields and particles. The proposal is that this conformal geometry provides a link between the remote infinitely expanded future of one universe phase (aeon) and a big-bang geometry of the next. The aeons join together in sequence, in this model, and it has something significant to say about all the puzzles mentioned above.